Abstract:

This invention is directed to implantable coils and, more particularly, to
a coil implant having a stretch-resistant member internal to the coil.
The implant of the invention is able to freely articulate and torque
prior to delivery. Once delivered, the implant is no longer stretch
resistant and is therefore able to substantially conform to the vascular
site.

Claims:

1. An implant, comprising:a primary coil defining a lumen disposed along
an axis, the primary coil having a proximal end defining a proximal
aperture and a distal end defining a distal aperture;a stretch-resistant
member disposed within the lumen;a member having a central axis that
intersects the proximal aperture, the member being coupled to the
stretch-resistant member within the lumen, and having an engagement
portion exterior the lumen wherein said engagement portion and said
member are capable of moving distally into the lumen; anda retainer
engaging the distal aperture and coupled to the stretch-resistant member
within the lumen.

2. The implant of claim 1, wherein the engagement portion and member is
capable of moving distally completely into the lumen.

3. The implant of claim 1 further comprisinga secondary coil further
defining the proximal aperture which coil is coaxial with the primary
coil and having a distal end and proximal end.

4. The implant of claim 3, wherein the primary coil has an outer and an
inner diameter and the secondary coil has an outer diameter which is
smaller than or equal to the inner diameter of the primary coil.

5. The implant of claim 3, wherein the proximal end of the primary coil is
adjacent to or partially envelopes the distal end of the secondary coil.

6. The implant of claim 3, wherein the primary coil and the secondary coil
are independently comprised of a metal wire.

7. The implant of claim 6, wherein the wire is comprised of a metal
selected from the group consisting of platinum, palladium, rhodium,
rhenium, iridium, gold, silver, tungsten, tantalum, an alloy of two or
more of these metals, or a super elastic metal.

8. The implant of claim 7, wherein the wire is a platinum alloy.

9. The implant of claim 3, wherein the primary coil and the secondary coil
is comprised of a primary helix which is itself wound and set into a
secondary shape.

10. The implant of claim 9, wherein the secondary shape is selected from
helical, spheroidal, cubic, and tertiary space-filling shapes.

11. The implant of claim 1, wherein the stretch-resistant member is
comprised of a polymer.

12. The implant of claim 11, wherein the polymer is biodegradable or
non-biodegradable.

13. The implant of claim 12, wherein the polymer is polypropylene.

14. The implant of claim 11, wherein the stretch-resistant member is
further comprised of a bioactive coating.

15. The implant of claim 14, wherein the bioactive coating is selected
from the group consisting of a growth factor, a gene, an oligonucleotide,
a peptide, a marine biopolymer, a monosaccharide, a disaccharide, a
polysaccharide, collagen and combinations thereof.

16. The implant of claim 1, further comprisinga plurality of fibers.

17. The implant of claim 16, wherein the fibers are wrapped around the
primary and/or secondary coil at least one time.

18. The implant of claim 16, wherein each fiber is wrapped around the
stretch resistant member at least one time.

19. The implant of claim 17 or claim 18, wherein each fiber is wrapped
around at least two times.

20. The implant of claim 16, wherein the fibers are comprised of a
copolymer of glycolic acid and lactic acid.

21. The implant of claim 20, wherein the fibers further comprise a
bioactive coating.

22. The implant of claim 21, wherein the coating is either a lubricious
hydrophilic coating and a hydrophobic coating.

23. The implant of claim 21, wherein the coating comprises a copolymer of
lactic acid and glycolic acid.

24. The implant of claim 16, wherein the fibers are comprised of a
biodegradable polymer.

26. The implant of claim 25, wherein the polymer is polyglycolic acid and
polylactic acid and is present in a ratio of polyglycolic acid and
polylactic acid selected from 99:1; 95:5, 90:10, 50:50, 10:90, 5:95, or
1:99.

27. The implant of claim 1, wherein the retainer has a portion that is
exterior the lumen of the primary coil.

28. The implant of claim 27, wherein the portion that is exterior has a
shape that is rounded.

29. The implant of claim 1, wherein the retainer is comprised of a
polymer.

30. The implant of claim 29, wherein the polymer is polypropylene.

31. The implant of claim 1, wherein the distal portion of the member
having a central axis that intersects the proximal aperture comprises an
eyelet.

32. The implant of claim 31, wherein the stretch resistant member is
coupled to the eyelet with a knot.

33. The implant of claim 32, where in the knot is a half-hitch or a hitch
knot.

35. A method of embolizing a vascular site in a patient, comprising
introducing to said site via a positioner an implant comprisinga primary
coil defining a lumen disposed along an axis, the primary coil having a
proximal end defining a proximal aperture and a distal end defining a
distal aperture;a stretch-resistant member disposed in the lumen;a
retainer engaging the distal aperture and coupled to the
stretch-resistant member within the lumen; anda member having a central
axis that intersects the proximal aperture at various points, the member
being coupled to the stretch-resistant member within the lumen, and
having an engagement portion exterior the lumen said member is capable of
moving distally into the lumen;thereby embolizing the vascular site.

36. The method of claim 35, wherein the implant substantially conforms to
the vascular site.

37. The method of claim 35, wherein the positioner is a microcatheter.

38. The method of claim 35, further comprising detaching said implant from
the positioner.

40. The method of claim 38, wherein after detachment, the member and
engagement portion is free to move within the lumen.

41. The method of claim 40, wherein after detachment the engagement
portion and member is contained in the lumen.

42. The method of claim 41 wherein the engagement portion is completely
contained in the lumen.

43. The method of claim 38, wherein the implant is stretch-resistant prior
to detaching from the positioner.

44. The method of claim 43, wherein the implant is no longer
stretch-resistant after detaching from the positioner.

45. The method of claim 38, further comprisingdelivering additional
implants.

Description:

RELATED APPLICATIONS

[0001]This application claims the benefit under 35 U.S.C. §119(e) of
provisional application Ser. No. 60/894,589 filed Mar. 13, 2007 and
60/894,858 filed on Mar. 14, 2007, both of which are hereby incorporated
by reference in its entirety.

FIELD OF THE INVENTION

[0002]This invention relates to implantable coils and, more particularly,
to a coil implant having a stretch-resistant member internal to the coil.

BACKGROUND OF THE INVENTION

[0003]Implants are delivered to a vascular site, such as an aneurysm, of a
patient via a microcatheter to occlude or embolize the vascular site.
Typically, the implant is engaged at the distal end of either the
delivery microcatheter or the guidewire contained within the
microcatheter and controllably released therefrom into the vascular site
to be treated. The clinician delivering the implant must navigate the
microcatheter or guide catheter through the vasculature and, in the case
of intracranial aneurysms, navigation of the microcatheter is through
tortuous microvasculature. This delivery may be visualized by fluoroscopy
or another suitable means. Once the distal tip of the catheter or
guidewire is placed in the desired vascular site, the clinician must then
begin to articulate the implant in the vascular site to ensure that the
implant will be positioned in a manner to sufficiently embolize the site.
Once the implant is appropriately positioned, the clinician must then
detach the implant from the catheter or guidewire without distorting the
positioning of the implant. Detachment may occur through a variety of
means, including, chemical detachment, mechanical detachment, hydraulic
detachment, and thermal detachment.

[0004]The procedure of delivering the implant to the vascular site can be
complicated for a number of reasons. One common complication found with
implants of the art is that the doctor is not able to effectively
articulate, rotate, and/or control the implant during positioning in the
vascular site to provide sufficient embolization. One reason that the
implant may not be able to effectively articulate is that the proximate
portion of the implants of the art are often rigid. This portion is
referred to as the "stiff zone" and may also contain the detachment
mechanism. One drawback of an implant having a "stiff zone" is that this
"stiff zone" may cause catheter kick-out after deployment of the implant
to the vascular site.

[0005]Another complication with implants of the art is that the implant
may not be able to substantially conform to the vascular site due the
presence of a stretch-resistant member. For example, U.S. Pat. No.
5,582,619 teaches a stretch-resistant member that is fixedly attached at
both ends or at one end and then at another point in the lumen of the
catheter. Due to the stretch-resistant member being fixedly attached in
two locations, the implant, after delivery, will maintain some
stretch-resistant properties. If the implant is stretch resistant after
delivery, this may inhibit the implant's ability to substantially conform
to the vascular site.

[0006]Yet another complication with implants of the art is that after
detachment, the implant may contain a traumatic (or sharp) portion or
stem. This traumatic portion most frequently occurs with implants that
are mechanically or electrolytically detached from the delivery device.
See, for example, U.S. Publ. 2004/0034363 which describes use of a
stretch-resistant member and a loop at the proximal end of the coil. The
loop, after deployment, is a traumatic portion. The traumatic portion may
cause damage to the patient in the surrounding vasculature. Further, it
is also contemplated that due to the presence of the loop, the clinician
is not able to torque the implant during delivery therefore making the
appropriate placement more difficult.

[0007]In light of the above, there exists a need for an implant that
maintains the ability to freely articulate and torque without having a
"stiff zone," and also for the implant to substantially conform to the
vascular site. There also exists a need to have an implant without a
traumatic portion or stem after detachment at the vascular site.

SUMMARY OF THE INVENTION

[0008]The invention is directed to, in one embodiment, an implant with a
stretch-resistant member.

[0009]The implant further includes a member for engaging a positioning
device or a positioner. The member for engaging a positioning device and
the stretch-resistant member are coupled together. The member for
engaging a positioning device is free to move with respect to the coil
thereby allowing for the implant to articulate and be positioned more
accurately. In one embodiment, the implant includes a primary coil that
defines a lumen disposed on an axis. A proximal end of the primary coil
defines a proximal aperture, and a distal end of the primary coil defines
a distal aperture. A stretch-resistant member is disposed in the lumen,
with a coupling portion of the stretch-resistant member coupled in the
lumen to the member for engaging a positioning device that has an
engagement portion exterior to the lumen. The stretch-resistant member
can be a line, a filament, or a braid.

[0010]The implant optionally can include a secondary coil. In one
embodiment, the secondary coil is disposed at least in part in the lumen,
and that further defines the proximal aperture. The secondary coil is
coaxial with the primary coil.

[0011]The coupling portion of the stretch-resistant member can be coupled
to a distal end of the member for engaging a positioning device which can
preferably be an eyelet. The stretch-resistant member can also couple to
the engagement member with a wrap or a knot, and can also extend back to
the distal end of the primary coil so that two lengths of line extend
along the length of the lumen. The line can also have an end that engages
a retainer at the distal end of the primary coil. In one embodiment, the
retainer is ball-shaped or rounded.

[0012]The member for engaging a positioning device can preferably be a rod
and have a proximal end with an engagement portion, and the engagement
portion can preferably be a ball mounted on the proximal end of the
member for engaging a positioning device. The member for engaging a
positioning device can also extend through the proximal aperture so that
the engagement portion is disposed at the proximal-most end of the
implant. The member for engaging a positioning device and the coupling
portion of the stretch-resistant member can be freely disposed at the
proximal end of the implant so that the member for engaging a positioning
device and the coupling portion are not connected to or attached to the
primary or secondary coils. Also, the member for engaging a positioning
device can have a central axis that intersects the proximal aperture at
various points. The member and engagement portion are free to move
distally into the lumen of the primary (or primary and secondary) coil.
In one embodiment, the member and engagement portion can move distally to
be completely in the lumen of the coil.

[0013]In another embodiment, the invention is directed to a method of
embolizing a vascular site in a patient. The implant is introduced to the
vascular site via a positioner and then detached from the positioner
thereby embolizing the vascular site. The implant can be detached from
the positioner by chemical detachment, electrolytic detachment,
mechanical detachment, hydraulic detachment, or thermal detachment. After
detachment, the engagement portion is contained within the interior
lumen. In one embodiment, the engagement portion is completely contained
within the interior lumen.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]The accompanying drawings, which are incorporated herein and
constitute part of this specification, illustrate exemplary embodiments
of the invention, and, together with the general description given above
and the detailed description given below, serve to explain the features
of the invention.

[0015]FIG. 1A is a plan view of an exemplary positioning system and a plan
view of an exemplary implant.

[0016]FIG. 1B is a closer view of a portion of FIG. 1A.

[0017]FIG. 2 is a plan view of a positioning system of FIG. 1 within the
human body.

[0018]FIG. 3 is a partial cross-sectional plan view of the implant of FIG.
1 with an exemplary positioning device.

[0019]FIG. 4A is a closer view of a portion of FIG. 2 showing the
positioning system in partial cross-section and an exemplary implant in a
position within the human body prior to deployment of the implant.

[0020]FIG. 4B is a closer view of a portion of FIG. 2 showing the
positioning system in partial cross-section and an exemplary implant in
another position within the human body after deployment but before
detachment.

[0021]FIG. 5 is a partial cross-sectional plan view of an implant with a
stretch-resistant member in partial cross-section.

[0022]FIGS. 6A and 6B show an implant of the invention prior to detachment
(FIG. 6A) and after detachment (FIG. 6B) from the positioner in partial
cross-section.

[0023]FIG. 7 is a plan view of an embodiment of the stretch-resistant
member of FIG. 5.

[0024]FIG. 8A illustrates one embodiment, in plan view, an exemplary
wrapping pattern of the fibers around the stretch resistant member.

[0025]FIG. 8B is a cross-sectional view of the wrapping pattern of the
fibers around the stretch-resistant member shown in FIG. 8A.

DETAILED DESCRIPTION OF THE INVENTION

[0026]Unless defined otherwise, all technical and scientific terms used
herein have the same meanings as commonly understood by one of ordinary
skill in the art to which this invention belongs. Although any methods
and materials similar or equivalent to those described herein can be used
in the practice or testing of the present invention, the preferred
methods, devices, and materials are now described. All publications and
patent applications cited herein are incorporated herein by reference in
their entirety. Nothing herein is to be construed as an admission that
the invention is not entitled to antedate such disclosure by virtue of
prior invention.

[0027]It must be noted that as used herein and in the appended claims, the
singular forms "a," "an," and "the" include plural references unless the
context clearly dictates otherwise.

Methods of Embolizing a Vascular Site

[0028]Prior to describing the embodiments of the implant of the invention,
provided below is an embodiment of the invention related to embolizing a
vascular site of a patient using an implant.

[0029]As illustrated in FIGS. 1A and 1B, the implant of the invention, in
one embodiment, may be used with a positioning device 70 that may
optionally include an actuator 90 operated by an operator, a positioning
tube 76 engaging the actuator 90, and an implant interface 78 at the
distal end of the positioning tube 76. A portion of the implant interface
78 engages a complementary portion of an implant 10. The positioning
device 70 is more specifically described below in FIG. 3.

[0030]In the embodiment illustrated in FIGS. 1A and 1B, an operator uses a
guide tube or guide catheter 12 to position a delivery tube or
microcatheter 14 in a patient's vasculature, as illustrated in FIG. 2.
The procedure involves inserting the guide catheter 12 into the patient's
vasculature through an access point such as the groin, and directing the
distal end 12a of the guide catheter 12 through the vascular system until
it reaches the carotid artery. After removing a guide wire (not shown)
from the guide catheter 12, a microcatheter 14 is inserted into the guide
catheter 12 and the distal end 14a of the microcatheter 14 subsequently
exits the guide catheter distal end 12a and is positioned near the target
site 16, such as an aneurysm in the patient's brain.

[0031]As illustrated in FIGS. 4A and 4B, the microcatheter 14 includes
microcatheter markers 15 and 15a that facilitate imaging of the distal
end 14a of the microcatheter 14 with common imaging systems and, in the
illustrated embodiment, the microcatheter markers 15 and 15a are made of
a radiopaque material. After the distal end 14a reaches the target site
16, the positioning device 70 (as shown in FIG. 1A) of the illustrated
embodiment is then inserted into the microcatheter 14 to position the
implant interface 78 at the distal end of the positioning device 70 near
the target site 16, as illustrated in FIG. 4B.

[0032]If the implant 10 is being delivered in the procedure, the implant
10 is attached to the implant interface 78 prior to inserting the
positioning device 70 into the microcatheter 14. This mode of implant
delivery is illustrated in FIGS. 2 and 4A-B. The delivery of the implant
10 is facilitated by disposing the microcatheter marker 15a near the
target site 16, and aligning the microcatheter marker 15 with a
positioner marker 15b in the positioner tube 76 which, when the two
markers (markers 15 and 15b) are aligned with each other as illustrated
in FIG. 4B, indicates to the operator that the implant interface 78 is in
the proper position for the release of the implant 10 from the
positioning device 70. After depositing the implant 10 at the target site
16, a second implant 10 can be deposited at the target site 16 by
removing the positioning device 70 from the microcatheter 14 and
inserting a second positioning device 70 with an attached second implant
10 into the microcatheter 14 in a manner similar to the method used with
the insertion of the first implant 10. The same procedure can be used for
a third implant 10 and subsequent implants if clinically necessary. If
the implant 10 is already in the patient's body to be retrieved or
repositioned, the positioning device 70 is inserted into the
microcatheter 14 without the implant 10.

[0033]As can be seen in FIG. 4A and FIG. 4B, it is advantageous that the
implant 10 and positioning device 70 (not shown) have a reduced "stiff
zone" at the interface 78 to better allow delivery through the tortuous
vasculature, responsive placement into the target site 16, and for the
ability to reposition the implant 10.

The Implant and Device Configurations

[0034]The implant of the invention maintains a high level of articulation,
including the ability to torque, prior to deployment thereby providing
responsive placement and repositioning prior to deployment. This level of
articulation is partially due to a lack of having or having a very small
"stiff zone" in its proximal end. Further and as explained below, in one
embodiment, the implant of the invention is stemless after detachment. As
a result of the implant being stemless, the level of trauma associated
with deployment of an implant in the vasculature is minimized.

[0035]Additionally, as described below, the implant of the invention has a
stretch-resistant member and this feature eases delivery by allowing the
clinician to reposition as necessary without the implant deforming while
maintaining its secondary shape. After the implant of the invention is
delivered, the implant of the invention no longer retains its "stretch
resistance" properties thereby allowing the implant to better
substantially conform to the vascular site.

[0036]The implant 10 illustrated in FIG. 5 includes a primary coil 20, a
secondary coil 30, a stretch-resistant member 40, a retainer 50, and a
member 60 for engaging a positioning device 70 (shown in FIGS. 1A, 1B,
and 3). The member 60 for engaging a positioning device 70 is preferably
a rod that includes a ball 62 and an eyelet 64.

[0037]The primary coil 20 has a proximal end 22 and a distal end 24
defining an internal lumen 26 extending between the ends of the primary
coil. The primary coil 20 can be formed in a variety of shapes once heat
setting of the coil form is performed. One such shape of the primary coil
can be found in U.S. Ser. No. 12/______ filed on even date herewith as
attorney docket number 355492-7601 and titled "An implant, a mandrel, and
a method of forming an implant." This application is incorporated by
reference into its entirety.

[0038]The optional secondary coil 30 is disposed at the proximal end 22 of
the primary coil 20 and further defines the proximal aperture. In one
embodiment, the secondary coil 30 has an outer diameter that is sized to
fit within the internal lumen 26 of the primary coil 20 and the primary
coil 20 partially envelops the secondary coil 30. In this embodiment, the
secondary coil 30 has an outer diameter which is less than the inner
diameter of the primary coil 20. In another embodiment, the secondary
coil 30 has an outer diameter equal or less than the outer diameter of
the primary coil 20. In another embodiment, the secondary coil 30 is
adjacent to the primary coil 20. The secondary coil 30 may be affixed by
any means, such as welded, to the proximal end 22 of the primary coil 20
with weld 36, with a distal portion 34 of the secondary coil 30 disposed
within the internal lumen 26 and a proximal portion 32 disposed proximal
to the primary coil 20.

[0039]The retainer 50 engages the distal end 24 of the primary coil 20.
The retainer 50, if present, is shaped such that there is minimized
trauma to the vascular site upon delivery. In certain embodiments, the
retainer 50 is ball-shaped. In some embodiments, the retainer 50 is
rounded on the portion that is exterior to the lumen 26 and the diameter
of the retainer 50 is equal to or slightly less that than the outer
diameter of the primary coil 20. The stretch-resistant member 40 is
disposed in the internal lumen 26. A distal end 44 of the
stretch-resistant member engages the retainer 50. A proximal end 42 of
the stretch-resistant member 40 engages the eyelet 64 of the rod 60. The
distal portion of the rod 60 and the eyelet 64 are disposed in the
internal lumen 26. A proximal portion of the rod 60 and the ball 62
extends proximally from the internal lumen 26 and is disposed proximal to
the primary and secondary coils 20 and 30. The rod 60 and the proximal
end 42 of the stretch-resistant member 40 are not connected to or
attached to the primary or secondary coils 20 and 30 and are free to move
within the internal lumen 26 in the direction of the longitudinal axis of
the implant 10 and to move so that the rod 60 can assume an angle
relative to the longitudinal axis of the implant 10.

[0040]The proximal end 42 of the stretch-resistant member 40 and the
eyelet 64 form a coupling that can comprise any type of connection. The
stretch-resistant member 40 is preferably a single line 46 that extends
from the retainer 50 to the eyelet 64, passes through the eyelet 64, and
extends from the eyelet 64 to the retainer 50. The line 46 can also be a
filament or a braid. When passing through the eyelet 64, the line 46 is
preferably wrapped through the eyelet 64 to form a knot 48, and is most
preferably formed as a hitch knot as illustrated in FIG. 7.
Alternatively, the line 46 can be one or more separate lines that
terminate at the eyelet 64 to form a coupling with the eyelet 64. In
another alternative, the coupling can be formed in the stretch-resistant
member 40 in a middle portion disposed between proximal and distal
portions of the stretch-resistant member 40, such as with a knot coupling
the proximal and distal portions of the stretch-resistant member 40
together within the internal lumen 26. In yet another alternative, the
coupling can be a combination of a knot and a wrapping, or a combination
of multiple lines 46 employing different couplings. The coupling can also
involve the modification of the stretch-resistant member 40 at the point
of coupling, such as by deforming or melting of the stretch-resistant
member 40 to join the end of a line 46 back onto itself to form a closed
loop. In still another alternative, an eyelet can be formed at the
proximal end of the stretch-resistant member 40 that is coupled to the
distal end of the rod 60, with the distal end of the rod 60 knotted to
form the coupling, or with the distal end of the rod 60 deformed or
melted back onto itself to form a closed loop.

[0041]The inner diameter of the secondary coil 30 is selected to engage
the eyelet 64 and to engage the positioning device 70 (shown in FIG. 1A).

[0042]The rod 60 can have various cross-sectional shapes, such as a
circular or triangular shape. The ball 62 can be replaced with another
structure such as a disc, hook, or ring structure that preferably
provides an external diameter or equivalent dimension comparable to the
ball 62.

Fibers

[0043]The primary coil 20, secondary coil 30, and the stretch-resistant
member 40 can also comprise at least one fiber 85. The fiber(s) 85 can be
a plurality of fibers, at least one bundle of fibers, or a plurality of
fiber bundles. The fiber(s) 85 can be enlaced, tied, or knotted to a
number of places on the implant 10. The fibers or fiber bundles 85 can be
disposed so that they are not tied or knotted to the implant 10, thereby
avoiding potentially obstructive bundles that might hinder deployment of
the implant 10 or might mechanically damage the implant 10. The use of
fibers with coils is disclosed in U.S. Publ. No. 2006/0036281, which is
incorporated by reference in its entirety.

[0044]In one embodiment illustrated in FIGS. 8A and 8B, the fiber 85 is
wrapped at least one or two times around the stretch-resistant member 40.
In one embodiment, the fiber(s) 85 include a plurality of fibers, at
least one bundle of fibers, or a plurality of fiber bundles wrapped at
least one or two times round the stretch-resistant member 40.

[0045]In another embodiment, the fiber(s) 85 are enlaced through a single
loop around the primary coil 20 and optionally the secondary coil 30. In
another embodiment, the fiber(s) 85 are enlaced through a pair of loops
of the primary coil 20 and optionally the secondary coil 30. In yet
another embodiment, the fiber(s) 85 are enlaced in a "S" pattern through
a plurality of loops in the primary coil 20 and optionally the secondary
coil 30. In still yet another embodiment, the fiber(s) 85 are enlaced
adjacent to each other in a "S" pattern on the primary coil 20 and
optionally the secondary coil 30.

Materials

[0046]The primary and secondary coils 20 and 30 and rod 60 are preferably
made of a biocompatible metal or metal alloy wire that does not react
adversely with tissues and fluids when used in the body. The wire may be
round, square, oval, triangular, or another shape. In certain embodiments
the wire commonly has a diameter of from about 0.025 to about 0.09 mm,
from about 0.03 to about 0.08 mm from about 0.04 to about 0.06 mm. In
certain specific embodiments the wire has a diameter of about 0.05 mm. In
some embodiments the wire may be comprised only of a primary shape e.g.,
a simple single helix. In some embodiments the wire component may
comprise a primary shape e.g., helical coil and a secondary shape which
the coil is biased to form upon release from the catheter or guidewire.
The secondary shape may comprise a complicated three dimensional shape.
These shapes include spherical, cubic and other space-filling shapes,
such as those created by winding the wire in a series of mobius loops.
This embodiment is described in can be found in U.S. Ser. No. 12/______
filed on even date herewith as attorney docket number 355492-7601 and
titled "An implant, a mandrel, and a method of forming an implant." This
application is incorporated by reference in its entirety.

[0047]In other embodiments the wire can comprise a coil of coils or double
helix. When it is a coil of coils, the outer or secondary diameter of the
outer helix may be from about 1 to about 25 mm in some embodiments and
from about 2 to 20 mm in certain other embodiments. The primary (inner)
helix may typically have an outside diameter of from about 0.1 to about
0.8 mm in some embodiments, and from about 0.15 to about 0.6 mm in other
embodiments and from about 0.2 to about 0.4 mm in yet other embodiments.
Certain specific embodiments provide for coils having a primary diameter
of about 0.28 mm sized to pass through a correspondingly dimensioned
catheter. Yet other embodiments provide for coils having a primary
diameter of about 0.24 mm sized to pass through a correspondingly
dimensioned catheter.

[0048]In one embodiment, the material of the primary and secondary coils
20 and 30 and rod 60 are made of a material that may be heat set at a
temperature of approximately 650° C. The metal or metal alloy can
be radiopaque so that the position and location of the implant in the
body can be monitored with radiological techniques. Suitable metals
include, but are not limited to the noble metals such as the platinum
group metals which include platinum, palladium, rhodium and rhenium as
well as iridium, gold, silver, tungsten, and tantalum and alloys of these
metals with one another. Additional metals include the super elastic
metals such as "Nitinol" and the like. In one embodiment, the primary and
secondary coils 20 and 30 are made of a platinum alloy, and the rod 60 is
made of stainless steel.

[0049]The overall axial length of the implant 10 of this invention ranges
from about 5 to about 400 mm in some embodiments and from about 10 to
about 300 mm in other embodiments. This length may be selected depending
upon the particular application of use and may be longer than about 400
mm in some embodiments.

[0050]The stretch-resistant member 40 and the retainer 50 are preferably
made from a wide variety of materials. These materials can include any of
the metals suitable for making the primary and secondary coils 20 and 30.
The stretch-resistant member 40 and the retainer 50 can also be made of a
radiopaque material, or of a polymer.

[0051]The stretch-resistant member 40, retainer 50, and fibers/fiber
bundles 85 are preferably made of polymeric materials, and most
preferably made of polypropylene. The retainer 50 is also preferably
formed from a melt of the stretch-resistant member 40. The polymeric
materials can include materials approved for use as implants in the body
or which could be so approved. They can be nonbiodegradable polymers such
as polyethylene, polyacrylics, polypropylene, polyvinylchloride,
polyamides such as nylon, e.g., Nylon 6.6, polyurethanes,
polyvinylpyrrolidone, polyvinyl alcohols, polyvinylacetate, cellulose
acetate, polystyrene, polytetrafluoroethylene, polyesters such as
polyethylene terephthalate (Dacron), silk, cotton, and the like. The
nonbiodegradable materials for the polymer component can comprise
polyesters, polyethers, polyamides and polyfluorocarbons.

[0052]The polymeric materials can be biodegradable as well. Representative
biodegradable polymers include: polyglycolic acid/polylactic acid (PGLA),
polycaprolactone (PCL), polyhydroxybutyrate valerate (PHBV),
polyorthoester (POE), polyethyleneoxide/polybutylene terephthalate
(PEO/PBTP), polylactic acid (PLA), polyglycolic acid (PGA),
poly(p-dioxanone), poly(valerolactone), poly(tartronic acid),
poly(β-malonic acid), poly(propylene fumarate), poly(anhydrides),
and tyrosine-based polycarbonates. Other equivalent materials, including
but not limited to stereoisomers of any of the aforementioned, may be
used as well. The biodegradable polymer can be comprised of copolymers of
lactic acid and glycolic acid. The copolymer can be comprised of
glycolic/lactic acid in the ratio of 90:10. The ratio of glycolic to
lactic acid can be chosen from 99:1; 90:10; 95:5; 50:50; 10:90; 5:95; and
1:99. The fibers can also be comprised of Nylon 6.6.

[0053]The stretch resistant member 40 and the fiber(s) 85 may also
comprise a bioactive coating. The bioactive coating may be selected from
growth factor, a gene, an oligonucleotide, a peptide, a marine
biopolymer, a monosaccharide, a disaccharide, a polysaccharide, collagen
and combinations thereof.

[0054]The illustrated stretch-resistant member 40 preferably has a tensile
strength of 0.2 and 1.2 Newton. In some embodiments, the tensile strength
is 0.6 Newton.

Positioning Device

[0055]The implant described herein may be delivered by a variety of
suitable microcatheters and positioning devices. In one embodiment, the
invention is directed to a kit having one or more implants of the
invention and a positioning device. In another embodiment, the kit
includes a microcatheter. Suitable microcatheters positioning devices are
described in WO 2007/121405 entitled "System and Method For Mechanically
Positioning Intravascular Implants" which is hereby incorporated by
reference in its entirety.

[0056]In one embodiment, as illustrated in FIG. 3, the implant 10 can
engage a positioning device 70 such that the ball 62 and the proximal
portion of the rod 60 engage the distal end 74 of the positioning device
70. The illustrated positioning device 70 can include a positioner 75
with a positioner tube 76 having an actuator interface 77 and an implant
interface 78 that terminates at an end cap 79. The end cap 79 can have a
port 80 through which the rod 60 communicates with the positioner lumen
81. The positioner 75 can also include a cord 82 that occludes a portion
of the port 80 to prevent the disengagement of the implant 10 from the
implant interface 78.

[0057]It is believed that, because the stretch-resistant member 40 resists
stretching, rod 60 is prevented from moving in the proximal direction out
of the secondary coil 30. However, as can be seen in FIG. 6A, the
stretch-resistant member 40, shown as line 46, remains sufficiently
flexible to allow the rod 60 and the ball 62 to assume an angled position
relative to the axis of the implant 10.

[0058]As can be seen in FIG. 6B, implant 10 can be mechanically released
from positioning device 70 by retracting cord 82 so that the aperture of
implant interface 78 is now sufficiently wide to permit ball 62 to
traverse therethrough whereupon implant 10 is released into the vascular
site. In this embodiment, ball 62 and rod 60 move in a distal direction
relative to the primary coil as described below or the primary coil 20
and secondary coil 30 move proximally relative to the ball 62 and rod 60.
Such movement places the ball 62 and rod 60 further into the internal
lumen 26 within the primary coil 20, and in some embodiments fully enter
the internal lumen 26 of the primary coil 20. In this case, ball 62 and
rod 60 are fully engulfed within lumen 26 so as to form a stemless
implant.

[0059]This flexibleness of the implant 10 of the invention reduces the
amount of catheter kick-out. Catheter kick out refers to the movement of
the catheter from its preformed shape after deployment of the implant and
is typically measured by the angle of deflection, shown in FIG. 4B as 92.
Implants of this invention typically have a catheter deflection of
40°, 30°, 20°, 19°, 15°, 10° or
less. This reduction of catheter kick out is at least a 20%, 30%, 40%,
50%, and even 60% improvement over implants of the art.

[0060]It is also believed that, when the implant 10 is a neurological
coil, the coil assumes two orientations, a microcatheter orientation when
disposed in a microcatheter and a deployed orientation when external to
the microcatheter. The transition of the coil from the microcatheter
orientation to the deployed orientation is believed to cause the primary
coil 20 to curve or bend and to extend slightly in length on at least one
side of the primary coil 20, while the stretch-resistant member 40 does
not so extend, thereby causing the proximal end of the implant 10 move
relative to rod 60 and ball 62 and surround the rod and ball. This
movement of the primary and secondary coils 20 and 30 relative to the rod
60 and ball 62, to enclose the rod and ball within the lumens of the
coils 20 and 30, is believed to advantageously provide a structurally
stable proximal implant end because any additional movement of the rod 60
and ball 62 is contained within the coils 20 and 30. It is further
contemplated that the implant 10 is better able to conform to the desired
vascular site.

Alternative Detachment Means

[0061]The implant may be deployed into the body by a number of means,
including, but not limited to electrolytic detachment, chemical
detachment, hydraulic detachment, thermal detachment, as well as other
types of mechanical detachments. It is contemplated that the implant
remains stemless after deployment into the body because after deployment,
the rod 60 and ball 62 will be displaced in the inner lumen of the
secondary coil 30. In other words, the ball 62 is drawn into the inner
lumen of at least the secondary coil 30.

[0062]Electrolytic detachment may be performed by providing a weakened
section at a junction between the implant 10 and the positioner 75.
Regardless of the junction, due to the stretch-resistant member, the rod
60 and ball 62 will still be displaced in the inner lumen of the
secondary coil 30 and possibly the primary coil 20. This weakened section
may be easily vaporized by application an electric current. For example,
the rod 60 and/or ball 62 may be replaced by a wire that may be detached
by an electrical force, such as a 9V electric power source that can apply
a current of about 0.3 milliamps for detachment. One example of an
electrical detachment mechanism is described in U.S. Pat. No. 5,928,226,
which is incorporated herein by reference.

[0063]With a chemical detachment mechanism, a dissolvable detachment
section is included between the positioning device 70 and the implant 10
or at the distal end of the positioner 75. The dissolvable detachment
section is dissolved, softened, swollen, degraded, or otherwise changed
by the injection of a biocompatible chemical through the catheter. After
the section is eroded, the rod 60 and ball 62 move distally into the
lumen of the secondary coil 30 or the primary coil 20 and secondary coil
30. Some examples of chemical detachment systems include dissolvable
detachment sections, such as a polymer section which is dissolved by
dimethylsulfoxide, a nylon section which is dissolved by a fluorinated
hydrocarbon, or sections which are dissolved by an aqueous saline
solution or any of the other biocompatible solvents discussed above.

[0064]A hydraulic detachment mechanism may also be used with the implant
of the invention. Hydraulic detachment means are within the scope of the
art. In one embodiment, the implant interface 78 is formed of a material
having a durometer such that when an appropriate fluid pressure is
applied to the interior of the positioning device 70, the implant
interface 78 expands thereby releasing the ball 62 and allowing the ball
62 to move distally into the lumen of the secondary coil and optionally
the primary coil.

[0065]The implant of the invention may also be configured to be thermally
detached from the positioner. This embodiment is similar to the
electrolytic detachment described above; however, instead of applying an
electric current, heat is applied thereby allowing the engagement portion
to detach from the position 70 and move distally into the lumen of the
catheter.

[0066]While the present invention has been disclosed with reference to
certain embodiments, numerous modifications, alterations, and changes to
the described embodiments are possible without departing from the sphere
and scope of the present invention, as defined in the appended claims.
Accordingly, it is intended that the present invention not be limited to
the described embodiments, but that it has the full scope defined by the
language of the following claims, and equivalents thereof.